The number 158
158 is a composite number with 4 divisors. Its prime factorisation is 2 × 79. Divisors (4): 1, 2, 79, 158.
Pick any whole number from 1 to 100,000.
How to work it out
- 1
What is special about 158: a semiprime: 2 × 79, the product of two primes.
- 2
158 is composite. Its prime factorisation is
- 3
The divisors add up to 240; without 158 itself that is 82, so 158 is deficient (82 is less than 158). Euler's totient φ(158) = 78 numbers up to 158 share no factor with it.
- 4
The digits of 158 add up to 14, and repeating that until one digit is left gives the digital root 5. The Collatz sequence (halve if even, else 3n+1) takes 36 steps to reach 1.
LaTeX source of the formulas on this page
\[ 158 = 2 \times 79 \]
158 at a glance
| Property | Value |
|---|---|
| Type | composite |
| Number of divisors | 4 |
| Sum of divisors | 240 |
| Euler totient φ(n) | 78 |
| Square | 24964 |
| Cube | 3944312 |
| Square root | 12.569805 |
| Digit sum / digital root | 14 / 5 |
| Collatz steps to 1 | 36 |
| Scientific notation | 1.58 × |
158 in other forms
| Form | Value |
|---|---|
| In words | one hundred and fifty-eight |
| Roman numerals | CLVIII |
| Binary (base 2) | 10011110 |
| Octal (base 8) | 236 |
| Hexadecimal (base 16) | 9E |
| Base 3 | 12212 |
| As time | 158 seconds = 2 min 38 s |
Is 158 divisible by 2 to 12?
| Divisor | Answer | Rule |
|---|---|---|
| 2 | Yes (158 ÷ 2 = 79) | A number is divisible by 2 if the last digit is even (0, 2, 4, 6, 8). |
| 3 | No (remainder 2) | A number is divisible by 3 if the digits add up to a multiple of 3. |
| 4 | No (remainder 2) | A number is divisible by 4 if the last two digits make a multiple of 4. |
| 5 | No (remainder 3) | A number is divisible by 5 if the last digit is 0 or 5. |
| 6 | No (remainder 2) | A number is divisible by 6 if it is divisible by both 2 and 3. |
| 7 | No (remainder 4) | A number is divisible by 7 if double the last digit and subtract it from the rest: the result is a multiple of 7. |
| 8 | No (remainder 6) | A number is divisible by 8 if the last three digits make a multiple of 8. |
| 9 | No (remainder 5) | A number is divisible by 9 if the digits add up to a multiple of 9. |
| 10 | No (remainder 8) | A number is divisible by 10 if the last digit is 0. |
| 11 | No (remainder 4) | A number is divisible by 11 if the alternating sum of the digits is a multiple of 11. |
| 12 | No (remainder 2) | A number is divisible by 12 if it is divisible by both 3 and 4. |
Questions
Is 158 a prime number?
No. 158 = 2 × 79, so it is divisible by 2.
What are the factors of 158?
1, 2, 79, 158.
What is 158 in binary?
10011110 (hexadecimal 9E, octal 236).
What is the square root of 158?
About 12.5698.
What is 158 in Roman numerals?
CLVIII.
Is 158 divisible by 3?
No. Its digits add up to 14, which is not a multiple of 3.
What is special about the number 158?
158 is a semiprime: 2 × 79, the product of two primes.